Design Pattern s - Creative Patterns- Factory Method
It is a mode of operation that replaces new. It can bring more scalability and fewer modifications to the system.

There are three kinds of factory modes: ordinary factory, multiple factory and static factory.

1. Ordinary factories

1.1. Description:
(1) Sender interface;
(2) MailSender implementation class;
(3) SmsSender implementation class;
(4) SimpleFactory simple factory.

1.2. Java implementation, code as follows:
(1)Sender

package com.java.designPattern.factoryMethod.simpleFactory;

/**
 * Interface
 *
 */
public interface Sender {

    public void send();

}

(2)MailSender

package com.java.designPattern.factoryMethod.simpleFactory;

/**
 * Implementation class
 *
 */
public class MailSender implements Sender {

    @Override
    public void send() {
        System.out.println("mail send !");
    }

}

(3)SmsSender

package com.java.designPattern.factoryMethod.simpleFactory;

/**
 * Implementation class
 *
 */
public class SmsSender implements Sender {

    @Override
    public void send() {
        System.out.println("sms send !");
    }

}

(4)SimpleFactory

package com.java.designPattern.factoryMethod.simpleFactory;

/**
 * Simple factory
 *
 */
public class SimpleFactory {

    public Sender produce(String senderName) {
        if ("mail".equals(senderName)) {
            return new MailSender();
        } else if ("sms".equals(senderName)) {
            return new SmsSender();
        } else {
            System.out.println("wrong parameter !");
            return null;
        }
    }

}

(5)Test

package com.java.designPattern.factoryMethod.simpleFactory;

/**
 * Test class
 *
 */
public class Test {

    public static void main(String[] args) {
        SimpleFactory factory = new SimpleFactory();
        Sender mailSender = factory.produce("mail");
        mailSender.send();
        Sender smsSender = factory.produce("sms");
        smsSender.send();
    }

}

Output:
mail send !
sms send !

2. Multiple factories

2.1. Description:
(1) Sender interface (same as 1);
(2) MailSender implementation class (same as 1);
(3) SmsSender implementation class (same as 1);
(4) Multiple factories of ManyFactory.

2.2. Java implementation, code as follows:
(1) Sender (same as 1)
(2) MailSender (same as 1)
(3) Sms Sender (same as 1)
(4)ManyFactory

package com.java.designPattern.factoryMethod.manyFactory;

/**
 * Multiple factories
 *
 */
public class ManyFactory {

    public Sender produceMail() {
        return new MailSender();
    }

    public Sender produceSms() {
        return new SmsSender();
    }

}

(5)Test

package com.java.designPattern.factoryMethod.manyFactory;

/**
 * Test class
 *
 */
public class Test {

    public static void main(String[] args) {
        ManyFactory factory = new ManyFactory();
        Sender mailSender = factory.produceMail();
        mailSender.send();
        Sender smsSender = factory.produceSms();
        smsSender.send();
    }

}

Output:
mail send !
sms send !

3. Static Factory (Recommendation)

3.1. Description:
(1) Sender interface (same as 1);
(2) MailSender implementation class (same as 1);
(3) SmsSender implementation class (same as 1);
(4) Factory static factory (two methods become static).

3.2. Java implementation, code as follows:
(1) Sender (same as 1)
(2) MailSender (same as 1)
(3) Sms Sender (same as 1)
(4)Factory

package com.java.designPattern.factoryMethod.factory;

/**
 * Static factory
 *
 */
public class Factory {

    public static Sender produceMail() {
        return new MailSender();
    }

    public static Sender produceSms() {
        return new SmsSender();
    }

}

(5)Test

package com.java.designPattern.factoryMethod.factory;

/**
 * Test class
 *
 */
public class Test {

    public static void main(String[] args) {
        Sender mailSender = Factory.produceMail();
        mailSender.send();
        Sender smsSender = Factory.produceSms();
        smsSender.send();
    }

}

Output:
mail send !
sms send !